The field of the invention pertains to fluid control valves and more particularly to an extractor valve assembly for controlling fluid flow in a fluid flow path.
Various types of control and/or shutoff valves have been developed for use in plumbing, drainage, irrigation and other fluid flow applications and systems. In particular, it is known for extractor or pinch valves to provide a useful method of controlling fluid flow in sealed conduit systems where contamination and leakage are critical factors, such as in vacuum-line systems. They provide a sanitary and self-contained method of controlling fluid flow by applying an external force to collapse a resiliently biasing/elastic valve material such that opposing inner side walls of the elastic extractor valve occlude flow therethrough.
For example, in U.S. Pat. No. 2,572,658, an automatic teat cup release device for milking machines is shown having a cylindrical body with nipples projecting at its opposite ends. A collapsible section or tube made of rubber extends through the cylindrical body and is fitted in the bores of the nipples. Furthermore, surrounding the cylindrical body is an outer contractible wall, also made of rubber or like material. The outer contractible wall houses an outer chamber in controlled fluid communication with the cylindrical body. Due to the collapsible section or rubber tube being interposed in a vacuum line, a sufficient increase in vacuum would, thus, cause fluid in the outer contractible wall to flow into the fluid chamber of the cylindrical body, thereby causing the collapse of the collapsible conduit or tube. Furthermore, a flexible or folding connection is positioned between the cylindrical body and the collapsible tube section and functions to maintain the tube section in a closed position when the teat cup is ready to be released. However, the flexible folding connection, which preferably consists of two pairs of arms or links 39, 40, function as follower arms, and are not utilized to effectuate the collapse of the collapsible tube section to occlude the flow path.
Additionally, in U.S. Pat. No. 3,498,316, a positive position extractor valve is shown having a rubber collapsible conduit which is molded in a nearly closed position to prevent the generation of large, short radius stresses at the reverse bends at the side edges of the flattened portions when in a closed position. Furthermore, the rubber valve has projections 30 integrally formed on diametrically opposite sides of the outer surface and are pierced by pins 32 and 60. The pin 60 is actuated by a T-shaped operator 40 to collapse the rubber conduit to an occluded position.
While the xe2x80x2658 and xe2x80x2316 patents illustrate two methods of applying extractor valves in a useful manner, they do not sufficiently address the adequacy of the pinch mechanism and/or elastic valve, to prevent leakage therethrough. For high pressure flow lines, flow seepage may occur at pinch corners of the elastic valve, thereby causing the walls of the elastic valve conduit to vibrate at a harmonic frequency, thereby causing a buzzing noise or honking sound. While the xe2x80x2316 patent attempts to prevent large, radius stresses from forming at the reverse bends of the pinched section, flow seepage may still occur at the corners. In fact, due to the pre-molded curvilinear shape of the pinch corners, any amount of pinching pressure may not be sufficient to completely occlude flow at the pinch corners.
It is an object of the present invention to provide an improved extractor valve assembly configured to more completely occlude a flow path when pinched, especially at the pinch corners.
It is a further object of the present invention to provide an improved extractor valve assembly having support tabs which provide improved distribution of pinching and release forces exerted by a pinching mechanism to prevent large pinch stresses from being concentrated at the pinch line.
The present invention is for an extractor valve assembly for controlling the flow in a fluid flow path. The extractor valve assembly comprises an elastic valve conduit, preferably made of rubber or like material, forming a flow passage through the elastic valve conduit. The elastic valve conduit is adapted to be interposed in the fluid flow path. Additionally, the elastic valve conduit has an outer surface with a pair of grooves formed on diametrically opposite sides thereof. The pair of grooves intersect a pinch circumference of the elastic valve conduit and is parallel to a central axis of the elastic valve conduit.
Furthermore, the extractor valve assembly also comprises means for releasably pinching the elastic valve conduit which is preferably a pair of pinch blades positioned along a pinch circumference of the elastic valve conduit. The blades are moved in a direction normal to a pinch line connecting the pair of grooves. In this manner, the resulting pinching action resiliently folds the elastic valve conduit along pinch corners formed at the pair of grooves and thereby releasably occludes the flow passage.